Feed system for automatic end point apparatus



J. c. RHODES 3,021,704

FEED SYSTEM FOR AUTOMATIC END POINT APPARATUS Feb. 20, 1962 4 Sheets-Sheet 1 Filed Dec. 9, 1959 TAIVD PIPE PRESSURE 6a ROl/C/N VAL "E 50L f/VO/D VflLVES NORMAL]. Y C L 0550 SOZFIVOIO 1691 V13 AOPIZOIZYCZOSID DRAIN INVENTOR. Joseph 6. Rhodes PE C ORDE E 54 CONDENSER 566 l 27 Dru/n ATTORNEY Feb. 20, 1962 J. c. RHODES 3,021,704

FEED SYSTEM FOR AUTOMATIC END POINT APPARATUS Filed Dec. 9, 1959 4 Sheets-Sheet 2 INVENTOR. Joseph 0. R/zades 5y Z ne-3T A 77' OR/VE Y Feb. 20, 1962 J. c. RHODES 3,021,704

FEED SYSTEM FOR AUTOMATIC END POINT APPARATUS Filed Dec. 9, 1959 4 Sheets-Sheet 3 INVENTOR. Joseph 0. Rhodes .4 T TORNEY J. c. RHODES 3,021,704 FEED SYSTEM FOR AUTOMATIC END POINT APPARATUS Feb. 20, 1962 Filed Dec. 9, 1959 4 Sheets- Sheet 4 STAND/12D LAMP STREAM 0% T0 PECORDEE LAMP M SOLE/V0105 so yo os INVENTOR. Jasepb 6. Alma es ATTORNEY 3,021,794 FEED SYSTEM FUR AUTOMATIC END POINT APPARATUS Joseph C. Rhodes, Park Forest, 111., assignor to Standard Oil Company, Chicago, 113., a corporation of Indiana Filed Dec. 9, 1959, Ser. No. 858,521 4 Claims. (Q1. 73-47) This invention relates to the automatic determination of the end point, i.e., the boiling point of the last volatile component of a mixture of liquids. More specifically, the invention relates to a system for measuring and recording the end point of a sample of a hydrocarbon distillate.

In the production of petroleum distillates, the primary specifications include those based on distillation properties. The high temperature end of a distillation curve is defined by specifying the maximum temperature permissible for a given product when distilled according to ASTM-procedures (ASTM Test D-158-53). This maximum temperature, obtained by distilling the product to dryness, is called the end point for that product.

Limitations are placed upon the end points of products, such as kerosenes and heater oils, to prevent contamination with higher boiling products. However, there frequently is considerable economic incentive to produce distillates having end points as close to the specification limit as possible. In order to approach such specification limits, it has heretofore been the practice to make laboratory analyses of grab samples, but such laboratory control of processing involves such long time lags between sampling, analysis, reporting and adjustment of the processing unit that close control of the'unit has been impossible. Consequently, the specification limit could not be as closely approached as might be desired because of danger of producing off-specification product while waiting for the laboratory results.

It is, therefore, a primary object of this invention to provide a system for automatic end point analysis which minimizes the time lag between samplingand process control.

Still another object of the invention is to provide an apparatus which will, in a continuous batch manner, determine the end point of a hydrocarbon distillate. A more particular object of the invention is to provide an apparatus which will automatically select and introduce a sample, determine the end point of the sample fluids, record the results of such determination, selectively check the operation of the analyzer, and if desired, automatically control the operating conditions of the processing unit which produced the hydrocarbon fluid under test. These and other objects of the invention will become apparent as the description thereof proceeds.

The instrument determines and records end points from 200 F. to 700 F. and the entire range can be covered by one instrument. The standard deviation between careful ASTM end point tests and data obtained on the instrument is about 2 percent of the span of the instrument. The error due to contamination is less than percent of the difference between the end points of successive samples. The reproducibility is 2 P. which is a precision that is at least as good as that obtained with the ASTM standard test.

The apparatus consists of a sample line, a flask in which the sample is contained for the determination of the end point, a low heat capacity heater capable of evaporating the sample to dryness, a thermocouple located to measure the temperature of the vapors flowing from the vapor arm of the flask, and a recorder to indicate such vapor temperature. Solenoid-operated valves control the flow into and out of the flask and a program timer controls thevariou's steps of the testing cycle. The distillationflask is preferably enclosed within a thermostatically-controlled chamber to reduce the eflects of ambient temperature changes.

The thermocouple and its lead wires are mounted directly in the vapor arm. A cooling coil is placed about the vapor arm near its junction with the distilling head and a filling line passing through the head introduces the sample near the bottom of the distillation flask. An asbestos ring is disposed between the bottom of the flask and the heater which may be supported by an adjustable post to permit quick replacement of the flask.

A test can be started by pressing a starter button located in the control room for the plant along with the recorder for the end point instrument. The instrument proper may be located at any selected point adjacent to the plant stream to be monitored.

When the test start switch is closed, a cycle timer begins operating to control the stream solenoid valves located on a sample circulation line. For a period of about seconds the fill solenoid valves are opened. The fill solenoid valves are then closed, and the drain solenoid valves remains open long enough to permit syphoning of the distillation flask to take place.

In addition, a known standard sample is provided for purposes of'checking the instrument. The operator can select between a stream test and a standard test by means of a selector also mounted in the control room. A reservoir of about five gallons of standard sample is maintained 1 adjacent the instrument.

The advantages and additional details of my apparatus will be described by reference to the accompanying drawing forminga part of this specification andwherein:

' FIGURE 1 is a schematic elevation of one embodiment of the invention;

FIGURE 2 is an elevation of a preferred embodiment of the invention;

FIGURE 3 is an enlarged detail view of the distillation unit employed in the apparatus of FIGURE 2; and

FIGURE 4 is a schematic electrical circuit diagram incctuding the program timer-employed in FIGURES 1 an 3. I

Referring to the drawing, the distillation unit includes the distillation flask 10 with its distilling head 11 including standpipe filling line 12, vapor outlet arm 13, thermocouple 14, and the valved siphon line 15. The thermocouple tip 14a is placed in the vapor arm 13 very close to the point where the vapor arm 13 joints the distillation head-11. It is recessed within the upper end of the vapor arm 13 just far enough to insure that the top 14a will be shielded from the direct radiation of the heater 16. In this manner, the thermocouple tip 14a receives its heat principally by convection from the passing vapors. It loses heat by radiation to the walls of the vapor arm 13 and by conduction through the thermocouple lead wires 18 which are provided with asbestos insulation 19. This conduction is minimized by using very fine (#30 gauge) thermocouple wire. When the flow of vapors is fast enough through the vapor arm 13, the thermocouple tip 14a is essentially at the vapor temperature. However, when the end point of the sample is reached, the vapor flow decreases substantially, the thermocouple tip 14a loses heat by radiation at such a rate that its temperature is reduced and signifies the maximum temperature attained in the test. This maximum temperature is the end point of the sample.

The flask heater 16 is adjustably supported below the flask 10 with an asbestos ring 19 therebetween. The heater 16 may be adjustably supported on a post 17 providedwith an indexing means. The asbestos ring 19 is similar to that used in the standard test and prevents excessive heating of the walls of the flask .10. The etfi- "ciencyof the heater 16 is decreased somewhat by the 3 ring 19 and the maximum obtainable liquid temperature would ordinarily be reduced. But this deficiency is counteracted by placing a deflector foil 20 underneath the plate or ring 19 to restore the efliciency of the heater 16. I a

It is essential in my apparatus that the temperature of the thermocouple 14 decrease when the end point is reached and overheating of the thermocouple 14 by radiation from the vapor arm 13 is avoided by providing the cooling 21 about the vapor arm 13 and passing cooling water through the coil 21. This cooling of the vapor arm 13 also serves to reduce the: temperature of the distillation head 11. This tends to increase the amount of recycling of condensed vapors during the test and assist in assuring correlation of the results with those of the ASTM test. The ring 19 in preventing excessive heating of the flask walls, further increases the amount of recycling.

The distilling head 11 includes an elongated generally tubular body 22 closed at its upper end and providing with an exterior standard tapered stopper portion 23. The filling line 12 enters the distilling head 11 and passes downwardly to a point near the bottom of the flask 10. The filling solenoid valves 24 and 24a on the filling line 12 are opened automatically when the stream test button is pushed and the sample runs into the bottom of the flask 10. The liquid rises in the flask and passes out through the vapor arm 13 which communicates with the distilling head 11 at an upper part thereof. About 100 cc. of sample is introduced into the flask 10 from filling line 12. The flask 10 has a capacity of about 50 cc. Any liquid residue which remains in the flask 10 from a previous test is washed up through the neck 10b of the flask 10, through the distilling head 11, and out the vapor arm 13. After suflicient flushing, solenoid valves 24 and 24a are closed, but drain solenoid valve 26 remains opened for a short period and the excess sample is siphoned from the flask 10 to the desired level (a volume of about 28 cc.) through a siphon tube which extends into the flask 10, upwardly into the distilling head 11 and into the drain line 27.

The flask heater 16 is adjustably supported below the flask 10 on post 17 provided with an indexing means and the entire distillation unit is arranged within a temperature-controlled and explosion-proof housing 31 which may be provided with window 31a and a space heater 33 controlled by space thermostat 34. An inverse thermostat 35 controls power to the circuit including the program timer 36 which is housed within explosion-proof box 35. The program timer box 37 and the distillation unit housing 31 are mounted within a cabinet 33 which also includes the associated circuitry and solenoid valve 26 on line 15.

The stream sample line 32 and the standard sample line 33 are connected to the filling line 12. The operator need not measure out a given volume of sample, but merely presses a starter button 55 or 55a which initiates the cycle control timer 36.

The program of operation as controlled by the cycle timer 36 includes a preliminary phase in which the sample is withdrawn from a stream sample circulation line 60 with which stream sample line 32 is connected. The stream sample line 32 includes a pressure-reducing valve 61, a pressure gauge 63, normally closed stream solenoid valve 24 and three-way stream solenoid valve 24a. In the closed position the port to line 12 is closed and the valve allows flow between the upstream port and drain line 32a. In the open position the port to line 32a is closed and the valve allows flow from the intake port to line 12. Thus when valves 24 and 24a are closed, any leakage from valve 24 will flow into the drain line 32a rather than into the fill line 25. The standpipe 25a prevents over-pressuring the flask 10 during filling in the event the drain lines 13 and 15 become plugged. When the test switch 55. or 55a is closed, the. cycle timer 36 begins operating, both the stream solenoid valves 24- 24a and 26 are opened for a period of 160 seconds. The stream solenoid valves 24 and 24a are then closed and the drain solenoid valve 26 is opened long enough to permit siphoning of the flask 10 as described.

A reservoir 65 of a standard sample/is provided for pudposes of checking the instrument. The reservoir 65 is connected to the standard line 33 which includes normally closed standard sample solenoid valves 66 and 66a. As in the case of the second sample valve 24a, the standard valve 66a is connected to the drain through drain line 33a thereby assuring that the standard liquid cannot flow into the instrument except when the selector switch 67 is actuated by the operator for the purpose of checking the instrument against the known standard sample.

The test switch 55 actuates the timer relay 40 which begins operation of the control timer 36 only if the system is at a high enough temeprature to actuate the inverse thermostat 35. Thus, I prevent operation of the test until the housing or box 31 has reached a preselected temperature. Further, no sample can be added during a heating or cooling period since the valves 24 and 24a remain closed and prevent the introduction of a subsequent sample from sample circulation line 60.

Actuation of the timer relay 40 initiates the program timer 36 for a single cycle of fifteen minutes, during which time the timer motor 41 and pilot light 42a or 42b receive power from switch 43 and the timer motor 41 rotates all the cams 44 on a common shaft 45. If the standard sample is being tested light 42b is on and if the stream sample is being tested light 42a is on.

At ten seconds after the test has been started, normally closed solenoid valves 24, 24a are opened for seconds and allow the sample to flow into fill line 12. seconds after the test has been started, the valve cam 44a deactuates switch 46, closes valves 24 and 24a, and opens valve 26 for 64 seconds, thus enabling simphoning to take place. 224 seconds after the test has been started, the heater control cam 44d actuates switch 47 which closes valve 26 and causes the heater relay 48 to switch power at 6.3 volts to the flask heater 16 through the transformer 49. The heater 16 remains on for 530 seconds. This is followed by a cooling period of 146 seconds which is terminated by the cycle timer cam 44 ending the fifteemminute test.

The flask 16 has a capacity of about 50 cc. and typically about 28.015 cc. of liquid remains in the flask after siphoning. The neck has a ground standard taper to insure fitting with corresponding taper 23 on the distilling head 11 and the center portion 10a of the flask 10 is silvered to reflect heat back to the sample.

The distilling head 11 is composed of stopper portion 23 and tubular body 22 which receives the fill line 12, the vapor tube 13 containing, the thermocouple 14, and the siphon tube 15. The thermocouple 14 is iron-constantan and the junction is located in vapor arm 13 as previously described. The lead wires 18 are sealed into sleeve 50 within tube 51 which merges with arm 13.

The heater 16 comprises a ribbon of Nichrome, which is coiled into a conical helix, and a stainless steel cup serving to support the Nichrome ribbon and to act as a heater reflector 52. The heater 16 is positioned with respect to the flask 10 by the post 17 and a heater-position coupling 53. The heater 16 may be lowered and pivoted outward about the post 17 to permit removal of the flask 10.

When the heater 16 is turned on, it raises the temperature of the sample within the flask 1i and distillation soon begins. The condensing vapors escape through the vapor arm 13 on the distilling head 11 and heat the thermocouple 14 located within the vapor arm 13. The reco d r 5 r co d h temp u f he e mo oup he r corde 54 s a con en ion po n iom er during the distillation is the end point of the sample.

Inverse thermoswitch 35 is mounted behind the flask 10 and its function is to prevent operation of the instrument until the temperature within the explosion proof housing 31 containing the distillation unit has reached 120 F. The temperature of the housing 31 is controlled at about 130 F. by thermostat 34 and space heater 33.

The stream solenoid valves 24 and 24a and drain valve 26 and standard sample valves 66 and 66a are explosion-proof and control the flow of the sample into and out of the flask 10 and are actuated by the program timer 36. The condenser 30 condenses the vapors escaping from the flask 10 via vapor tube 13 and may be cooled by water introduced via line 56 extending through the wall of the explosion-proof housing 31.

The test switch 39 is actuated by depressing the push button 55 or 55a, thereby initiating a fifteen-minute testing cycle by actuating the timer relay 40 which causes switch 47 to carry power to the timer motor 41 for a fifteen-minute period which is maintained and terminated by means of the timer relay cam 44.

Referring to the drawings, the operator selects a stream sample or a standard sample by positioning selector 63 to close stream switch 39 or standard switch 67. He then depresses the push button switch 55a. The pilot light 42a or 42b in the control room indicates which test is in progress.

If stream switch 39 is closed, the program timer 36 opens the solenoid valves 24 and 24a allowing the sample to flow from fill line 12 into the flask 10 and out the vapor tube 13 after the flask 10 is filled. The solenoid valves 24 and 24:: are closed and solenoid valve 26 opens causing the sample to be siphoned from flask 10 by line 15 to the desired level. The heater 16 is then turned on and solenoid valve 26 is closed. After a total operation of about fifteen minutes, the program timer 36 stops, the pilot light 42a or 42b is turned off, and the instrument is ready to receive another sample.

This application is a continuation-in-part of my copending application Serial No. 652,391, filed April 12, 1957, issued as U.S. Patent 2,967,423.

Although my invention has been described with reference to specific embodiments thereof, it should be understood that these are by way of illustration only and that modifications are contemplated without departing from the spirit of our invention.

What I claim is:

1. An apparatus for determining the end point of a process liqud in a flowing stream which comprises in combination a distillation unit, supply conduit means comprising a standpipe and discharging into said distillation unit, reservoir means for standard sample liquid, first valved conduit means communicating between said reservoir and said supply conduit means, first and second valve means in said first conduit means, process liquid circulation sample line means, second valved conduit means between said circulation line means and said supply conduit means, siphon tube means extending from the interior of said distllation unit, vapor line means discharging from said distillation unit, temperature responsive means disposed in said vapor line means, third valve means on said siphon tube means, fourth and fifth valve means in said second valved conduit means, electrical heating means for said distillation unit, temperature indicating means associated with said temperature responsive means, and program timer means, said valve means and said heating means being controlled by said program timer means.

2. An apparatus for determining the end point of a process liquid which comprises in combination a miniature distillation unit, standpipe means discharging into said distillation unit, reservoir means for standard liquid, first valved conduit means communicating between said reservoir and said standpipe, process sample circulation line means, second valved conduit means between said circulation line and said standpipe, siphon tube means discharging from a lower portion of the distillation unit, a vapor line discharging from said distillation unit, thermocouple means disposed in an upper part of said .vapor line, a first solenoid valve on said siphon tube means, second and third solenoid valve means on each of said valved conduit means, electrical heating means for said distillation unit, said solenoid valve means and said heating means being controlled by program timer means, and temperature indicating means associated with said thermocouple means.

3. The apparatus of claim 1 wherein said temperature responsive means comprises a thermocouple.

4. The apparatus of claim 2 which includes cooling means on said vapor line down-stream of said thermocouple means.

References Cited in the file of this patent UNITED STATES PATENTS 1,266,315 Raddant May 14, 1918 1,632,748 Parsons et a1. June 14, 1927 2,069,490 Zenske Feb. 2, 1937 

